Production of container-grown plants generally involves applying production solutions, such as water and liquid fertilizers, to individual containers with open root zones (that is, an open top surface and a draining bottom surface). Solutions are applied to the top surface of the open root zone by either overhead irrigation or drip irrigation techniques. Alternatively, the bottom surface of the root zone may be irrigated by capillary or sub-irrigation techniques. Examples of overhead spray or drip-watering techniques are disclosed in U.S. Pat. No. 4,584,791 (Wolf) or U.S. Pat. No. 4,177,604 (Friesen). Examples of such irrigation systems are found in the following U.S Pat. No. 4,729,189 (Whitcomb); U.S. Pat. No. 4,546,571 (Scrivens); U.S. Pat. No. 4,279,101 (Leroux); U.S. Pat. No. 4,211,037 (Green); U.S. Pat. No. 4,183,176 (Barfield); and U.S. Pat. No. 3,686,792 (Barfield).
Irrespective of the technique used for delivering water and nutrients to the container-grown plants, it is generally desirable to supply water to the plants in a manner that minimizes water loss through leakage, overspraying or evaporation. Preferably, irrigation systems for container-grown plants should be "closed", so that any applied water that is not retained by the plant containers is saved and recirculated.
Individual pallets for container-grown plants should be configured for integration with large numbers of pallets that are served by a single irrigation system. Moreover, individual pallets should be constructed so that they are readily removed from the irrigation system, and so that removal of one pallet does not interfere with the irrigation of the plants in the remaining pallets. Moreover, individual pallets should be constructed so that removal of one or more plants from the pallet does not interfere with irrigation of the plants remaining in the pallet. Preferably, the pallets should be lightweight and easy to handle.
Plant growth is enhanced whenever the plants are protected from extreme ambient temperature changes. Accordingly, a pallet or similar device for container-grown plants should provide a mechanism for insulating the plants from extreme changes in ambient temperature.